2018/03/09 by L. Coccato, Lodovico Coccato, Maximilian Fabricius +9
Physics and Astronomy · #Adaptive optics and wavefront sensing #Astronomy #Astrophysics #Bulge #Disc galaxy #Galaxies: Formation, Evolution, Phenomena #Galaxy #Galaxy formation and evolution #Hubble sequence #Luminosity #Metallicity #Physics #Population #Spiral galaxy #Star formation #Stars #Stellar population #Stellar, planetary, and galactic studies #astro-ph.GA
paper · pdf · doi:10.1093/mnras/sty705
13 pages, 11 figures, accepted for publication in MNRAS
arxiv created 2018/03/09 · openalex publication_date 2018/03/15 · arxiv updated 2018/03/28 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
We study the kinematics and the stellar populations of the bulge and disc of the spiral galaxy NGC 3521. At each position in the field of view, we separate the contributions of the bulge and the disc from the total observed spectrum and study their kinematics, age, and metallicities independently. Their properties are clearly distinct: the bulge rotates more slowly, has a higher velocity dispersion, and is less luminous than the disc. We identify three main populations of stars in NGC 3521: old (≥7 Gyr), intermediate (≈3 Gyr), and young (≤1 Gyr). The mass and light of NGC 3521 are dominated by the intermediate stellar population. The youngest population contributes mostly to the disc component and its contribution increases with radius. We also study the luminosity-weighed properties of the stars in NGC 3521. Along the photometric major axis, we find (i) no age gradient for the stars in the bulge, and a negative age gradient for the stars in the disc; (ii) negative metallicity gradients and subsolar α-enhancement for both the bulge and the disc. We propose the following picture for the formation of NGC 3521: initial formation a long time ago (≥7 Gyr), followed by a second burst of star formation or a merger (≈3 Gyr ago), which contributed predominantly to the mass build-up of the bulge. Recently (≤1 Gyr), the disc of NGC 3521 experienced an additional episode of star formation that started in the innermost regions.